1955. Boss, I Can See You!

Time limit: 1.0 secondMemory limit: 64 MB

— Oh, Boss, I can see you!
— Analogously!
From the animated film 'Investigation Held by Kolobki'

During their investigation, detectives Boss and Colleague got into an
empty warehouse to look for evidence of crime. The warehouse is
a polygon without self-intersections and self-tangencies,
not necessarily convex. The detectives investigate the territory of
warehouse in such a way that each of them can always see the other one.
Boss and Colleague can see each other if all the points of a segment
connecting them lie either inside the warehouse or on its border.
Find the maximal possible distance between the detectives.

Input

The first line of input contains an integer n: the number of vertices
of the polygon (3 ≤ n ≤ 200).
Next n lines contain two integers xi, yi each: coordinates
of vertices in clockwise or counterclockwise order
(−1000 ≤ xi, yi ≤ 1000).
It is guaranteed that polygon has neither self-intersections
nor self-tangencies.

Output

Output the maximal possible distance between Boss and Colleague.
The answer must be given with absolute or relative error
not exceeding 10−6.